Complete mitochondrial genome and phylogenetic analysis of Mastax latefasciata Liebke 1931 (Insecta: Coleoptera: Carabidae)

Abstract The genus Mastax Fischer von Waldheim 1827 belongs to the family Carabidae. Specimens of adult Mastax latefasciata Liebke, 1931 were collected from Yājì Hill, Huáihuà City, Húnán Province, China. The complete mitochondrial genome (GenBank accession number ON674050.1) of M. latefasciata was sequenced, annotated, and characterized. The results showed that it was a circular DNA molecule of 16,735 bp with 81.07% AT content and comprised 13 protein-coding genes (PCG), 22 tRNA genes, 2 rRNA genes, and 1 control region. The PCGs were initiated using typical ATN (Met) and TTG (Met) start codons and terminated using typical TAN stop codons. The phylogenetic position of Mastax within the Carabidae was first evaluated using complete mitogenomes, and the results showed that it was close to Cicindela anchoralis and Manticora tibialis.

The genus Mastax Fischer von Waldheim 1827 belongs to the tribe Brachinini of the family Carabidae (Liang and Yu 2004), and eight species have been recognized in China (Liang and Yu 2004). Jedli cka in Eastern Asia provided a key for Mastax latefasciata Liebke, 1931(Liebke 1931Liang and Yu 2004), which is the basal half of the elytra with one yellow square band and a band width of approximately two-fifths the length of the elytra (Liang and Yu 2004; Figure 1). At present, the nucleotide database of the National Center for Biotechnology Information (NCBI) has not publicly published the mitochondrial information of the genus Mastax, with the exception of the 16S ribosomal RNA (rRNA) gene of M. formosana. M. latefasciata is relatively common and readily available in China. In this study, the complete mitochondrial genome (mitogenome) of M. latefasciata was first sequenced, annotated and characterized, which would have significance for contributing to the research on phylogenetic position of the genus Mastax.
All 13 PCGs had a typical ATN (Met) start codon, with the exception of nad1 (a typical TTG start codon): seven PCGs (nad2, cox1, atp8, nad3, nad5, nad4l, and nad6) initiated with an ATT start codon; five PCGs (cox2, atp6, cox3, nad4, and  cob) initiated with an ATG start codon. All 13 PCGs contained a typical TAN stop codon: cob terminated with a TAG stop codon; seven PCGs (nad2, atp8, atp6, nad3, nad4l, nad6, and nad1) ended with a TAA stop codon; five PCGs (cox1, cox2, cox3, nad5, and nad4) terminated with an incomplete stop codon (T), consisting of a codon that was completed by the addition of A nucleotides at the 3 0 end of the encoded mRNA. The 22 tRNA ranged from 61 (trnA-UGC) to 71 bp (trnQ-UUG and trnK-CUU). The rrnL and rrnS were 1319 and 781 bp in length, respectively. The CR, also an AT-rich region, was 1,890 bp in length with an 88.78% AT content and located between the rrnS and trnI-GAU genes.
For phylogenetic analyses, mitogenomes of 16 Carabidae species and two outgroup species [Morphostenophanes sinicus (MW853764.1)  and Lepisma saccharina (MT108230.1) (Bai et al. 2020)] were used to evaluate the phylogenetic relationships within the Carabidae using MEGA v11.0.13 (Tamura et al. 2021). The amino acid sequences of 13 PCGs in their mitogenomes were aligned using MEGA (Tamura et al. 2021) with the MUSCLE program (Edgar 2004) using default specifications. The maximum-likelihood (ML) model with the lowest Akaike Information Criterion corrected (AICc) score was considered to be the best. Based on the AICc value (88830.21), general reversible mitochondrial model (mtREV24) with amino acid frequencies (þF), gamma distribution (þ G, parameter ¼ 0.4951, five rate categories) and invariant sites (þI, 22.29% sites) was chosen as the optimal phylogenetic model with 500 bootstrap replications for phylogenetic analysis (Figure 3). The structure of the phylogenetic tree is similar to reported in previous studies (Yu et al. 2019). The phylogenetic position of Mastax within the Carabidae was first evaluated using complete mitogenomes, and the results showed that it was close to Cicindela anchoralis and Manticora tibialis. In this study, the complete mitogenome characteristics of M. latefasciata would improve the understanding of the evolution of this species and phylogenetic position of the genus Mastax with the related taxa.

Ethical approval
This research does not involve ethical research. Insects are invertebrates, and there are no ethics involved in using them in experiments.

Author contributions
Yu Bai, analyzed the data, uploaded the analysis data, involved in certain tools for analysis, drafted of the paper, and approved the final draft. Lin Ye, collected and analyzed data. Kang Yang, performed the experiments and analyzed data. Xuyuan Gao, identified insects, contributed reagents/ materials, involved in conception and design of the work, performed the experiments, prepared figure, and approved and published the final draft. All authors agree to be accountable for all aspects of the work.

Disclosure statement
No potential conflict of interest was reported by the author(s).

Data availability statement
The genome sequence data that support the findings of this study are openly available in GenBank of NCBI at https://www.ncbi.nlm.nih.gov under the accession no. ON674050.1. The associated BioProject, Bio-Sample, and SRA numbers are PRJNA857156, SAMN29618062, and SRR20082406 respectively.